Hydraulic hand pumps in which a hand operated lever is pivotable against a plunger of a pump, which may be either a two stage or a single stage pump, are well known. In most such pumps, the pivot point of the lever is fixed regardless of the output pressure of the pump. However, it has been recognized that reducing the distance between the lever pivot point and pump plunger reduces the amount of force required to be applied to produce a given pressure. In most systems of this type, a compensation cylinder is subjected to the output pressure of the pump, and the lever is pivoted to a plunger of the compensation cylinder, so that as the compensation cylinder extends, it moves the lever pivot point toward the pump plunger, thereby reducing the moment arm between the lever pivot point and the pump plunger to reduce the force required to operate the pump. Such a patent, for example, is U.S. Pat. No. 3,792,747, the disclosure of which is hereby incorporated by reference in its entirety.
Such systems result in lateral loading on the compensation cylinder and premature failure. The present invention addresses these concerns.